The present invention relates to a lens array; a light emitting diode (LED) head including the lens array; an exposure device including the lens array; an image forming apparatus including the exposure device; and a reading apparatus including the lens array.
A conventional lens array is used as an optical system capable of forming an erected same-size image of an object, and is arranged in a line arrangement in an image forming apparatus of an electro-photography type or a reading apparatus such as a scanner and a facsimile. The image forming apparatus uses an LED (Light Emitting Diode) head in which a plurality of LEDs is arranged linearly. In the reading apparatus, an image of an original is formed on a light receiving unit formed of a plurality of light receiving elements arranged linearly.
The conventional lens array includes a lens group formed of a plurality of lenses for forming an erected same-size image of an object. The lens groups are arranged substantially linearly, so that the erected same-size image of an object is formed in a linear arrangement. The lenses may be integrally produced through a plastic injection molding, thereby reducing a number of parts (refer to Patent Reference).
Patent Reference: Japanese Patent Publication No. 2008-87185
In the conventional lens array, when light leaks from one of the lenses arranged linearly and is incident on another of the lenses, an image called a ghost, i.e., another image of the object, may be formed on an image plane. When the ghost is formed, an exposure device of the image forming apparatus forms an image with low contrast, thereby deteriorating image quality, or it is difficult for the reading apparatus to accurately obtain image data corresponding to an original.
In view of the problems described above, an object of the present invention is to provide a lens array capable of solving the problems of the conventional lens array and forming an image with high contrast.
Further objects and advantages of the invention will be apparent from the following description of the invention.